Cartridge-based analytical instrument with rotor balance and cartridge lock/eject system

ABSTRACT

The instrument includes a cartridge carousel assembly which receives analytical cartridges. The cartridges are self-contained units which incorporate a sample metering/separation system which is operated by centrifugal force. The cartridge carousel is composed of a cartridge rotor plate which includes a center and a plurality of cartridge ports which are located in spaced relation radially outward from the center of the plate. The cartridge ports include a cartridge dock which is shaped to receive the cartridges and a balance weight dock which is located radially inward from the cartridge dock. The cartridge dock is shaped to receive a balance weight. A locking mechanism is provided which holds the cartridge in the cartridge dock during rotation of the cartridge rotor plate. A balancing mechanism is provided which includes a balance weight which is movable to the balance weight dock when a cartridge is inserted into the cartridge dock. An ejection mechanism is provided which ejects the test cartridge from the cartridge port after processing of the test cartridge is completed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to systems and methods which areused to analyze fluids which may or may not contain solid components.More particularly, the present invention relates to instruments andmethods which are used in clinical laboratories and other healthcarelocations to analyze blood and other bodily fluids.

2. Description of Related Art

Clinical chemistry involves the qualitative and quantitative analyses ofbody fluids, such as blood, urine, spinal fluid and other materials.Clinical chemistry encompasses multiple specialty testing areasincluding coagulation, hematology, immunochemistry, as well aschemistry. The test results derived from such analyses are used byphysicians and other healthcare professionals to diagnose, monitor andtreat diseases. The analysis protocols, instrumentation and otherequipment utilized in clinical laboratory testing must be capable ofproviding accurate and repeatable test results. In addition, it isdesirable that the procedures and instrumentation be simple andefficient. The testing equipment and procedures should be versatileenough that they can be used in healthcare locations where relativelyfew samples are tested as well as in larger clinical laboratories wherethe number of samples being tested on a daily basis is quite large.

Another consideration in designing analytical equipment for use byhealthcare personnel is the amount of sample available for testing. Inmany situations, the amount of blood or other bodily fluid available isrelatively small. Accordingly, there has been a trend in clinicalchemistry to develop analytical systems which are capable of conductingnumerous different chemical analyses on relatively small amounts ofsample. In general, the goal has been to develop clinical analyticalsystems which provide the maximum number of medical tests utilizing theminimum amount of sample. In such systems, it is essential that thesample be accurately metered to provide a precise aliquot of sample fortesting.

In achieving the above goals, a multitude of different analyticalprocedures and approaches have been investigated. In one approach,instruments have been developed which have a single sample introductionsite. The equipment is designed so that the sample is split, metered androuted to various locations within the system where multiple chemicalanalyses take place. Other systems do not include internal samplesplitting/metering devices and rely on the clinical chemist to separatethe sample into small aliquots which are introduced into variousinstruments which are capable of conducting a maximum of only a fewchemical analyses at one time.

There is a continuing need to develop and provide clinical chemistryinstruments which are not only accurate, but versatile enough to meetthe demands of modern medicine. The instruments should be simple enoughto be used by not only highly-skilled laboratory technicians, but alsoby other healthcare personnel who may only be required to conductlaboratory tests intermittently. The instruments and procedures shouldbe compact and versatile enough so that they can be utilized in clinicallaboratories which analyze thousands of samples daily, while at the sametime being adaptable to doctors' offices, home healthcare agencies andnursing homes where the number of tests being conducted is not as great.In addition, the instruments should be versatile enough to be useful inconducting a wide variety of blood analyses which are presently beingroutinely utilized. The instruments should also be adaptable toconducting blood or other bodily fluid tests which will be developed inthe future.

SUMMARY OF THE INVENTION

In accordance with the present invention, an analytical instrument isprovided which is compact and versatile. The instrument is a“cartridge-based” instrument in that it is designed to receive andprocess individual self-contained cartridges which are pre-loaded withsample and any required reagents. The instrument utilizes centrifugalforce to process the test cartridges during the analysis process. Theinstrument is capable of simultaneously analyzing multiple testcartridges. The multiple test cartridges may be set up to conduct thesame or different analytical tests. The instrument is extremelyversatile because the cartridges are designed to carry out a widevariety of test protocols.

The instrument includes a cartridge carousel assembly which receivesanalytical cartridges. The cartridges are self-contained units whichincorporate a sample metering/separation system which is operated bycentrifugal force. The cartridge may also include a sample transportsystem which is operated by externally-applied pressure wherein thesample is transferred to a test element which provides a detectableanalytical property of the fluid sample. The cartridge carousel iscomposed of a cartridge rotor plate which includes a center and aplurality of cartridge ports which are located in spaced relationradially outward from the center of the plate. The cartridge portsinclude a cartridge dock which is shaped to receive the cartridges and abalance weight dock which is located radially inward from the cartridgedock. The cartridge dock is shaped to receive a balance weight.

The cartridge carousel assembly further includes a rotary drivemechanism which rotates the cartridge rotor plate about the centerthereof. It is this rotation of the cartridge rotor plate which operatesthe analytical system of the test cartridges. A locking mechanism isprovided which holds the cartridge in the cartridge dock during rotationof the cartridge rotor plate. Further, a balancing mechanism is providedwhich comprises a balance weight wherein the balance weight is movableto the balance weight dock when a cartridge is inserted into thecartridge dock. The mechanism is designed so that the balance weightremains in the cartridge dock during rotation of the cartridge rotorplate if a cartridge is not present in the cartridge dock. In this way,the cartridge rotor plate is automatically balance regardless of thenumber of cartridges which are placed in the cartridge ports.

As a further feature of the present invention, an ejection mechanism isprovided which ejects the test cartridge from the cartridge port afterprocessing of the test cartridge is completed. A detector is includedwhich measures detectable analytical properties of fluid samplesexhibited by the test elements of the cartridges. Further, a trackingand control unit is provided which tracks and controls the rotary drivemechanism, locking mechanism and ejection system.

The analytical instrument in accordance with the present invention iswell-suited for conducting a wide variety of clinical tests. Theversatility of the instrument is only limited by the different types oftest cartridges. The instrument is compact and simple to use.Accordingly, it can be used in a wide variety of settings ranging fromlarge clinical laboratories which conduct thousands of tests daily tosmall hospital laboratories or doctors offices.

The above discussed features and attendant advantages of the presentinvention will become better understood by reference to the followingdetailed description when taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred exemplary analyticalinstrument in accordance with the present invention showing the outerhousing thereof. Also shown in FIG. 1 are analytical cartridges whichare designed to be processed by the instrument.

FIG. 2 is a perspective view of an analytical instrument in accordancewith the present invention wherein the housing cover and user interfacehas been removed.

FIG. 3 is a top view of the preferred exemplary analytical instrumentshown in FIG. 2.

FIG. 4 is a perspective view of the preferred exemplary instrument inwhich the top portion has been removed to expose the cartridge rotorplate.

FIG. 5 is a view of the rotary drive mechanism and real time processingunit which is located at the bottom of the instrument as shown in FIGS.2-4.

FIG. 6 is a detailed view of the cartridge rotor plate.

FIG. 7 is a detailed view of the cartridge rotor plate which shows thelocking mechanism which holds the cartridge in place during rotation ofthe cartridge plate as well as the balancing mechanism which ensuresthat the rotor plate is balanced to ensure non-asymmetric rotation.

FIG. 8 is an exploded view of a preferred exemplary analytical cartridgewhich includes a test element which is designed to be used with areflectance detector system.

FIG. 9 is a side view of the reflectance test cartridge shown in FIG. 8.

FIG. 10 is a bottom view of the reflectance cartridge shown in FIG. 8.

FIG. 11 is a perspective view of a preferred exemplary test cartridgewhich includes a pressure-operated reagent transport system and anelectrochemical test element.

FIG. 12 is a view of the cartridge shown in FIG. 8 showing a bar codereading strip which is used by the instrument to provide tracking andcontrol of cartridge processing.

FIG. 13 is an exploded view of the electrochemical cartridge shown inFIG. 11.

FIG. 14 is an exploded view of the electrochemical cartridge of FIG. 11showing the electrochemical test element.

FIG. 15 is a partially exploded view of an analytical cartridge inaccordance with the present invention which includes a cuvette testelement which allows transmittance-based detection by the analyticalinstrument.

FIG. 16 is a detailed view of the cuvette which forms part of thetransmittance analytical test cartridge shown in FIG. 15.

FIG. 17 is a sectional view of FIG. 16 which depicts the pathway oflight through the cuvette detector.

FIG. 18 is a bottom view of the upper housing plate which is located ontop of the cartridge rotor plate. This figure depicts a septum actuator,vent seal element and actuator mechanism which form part of the sampletransport system which contact the cartridges during processing by theinstrument. The figure also depicts the actuator mechanisms whichactuate the reagent transport system in the cartridge.

FIG. 19 is an exploded view of the optical detection unit which islocated at a position within the analytical instrument below thecartridge rotor plate.

FIG. 20 shows the elements of the electrochemical detection system whichare located in the lower housing of the preferred exemplary instrument.

FIG. 21 is a more detailed view of FIG. 20 showing the electrochemicalcontact pins and actuator assembly.

FIG. 22 shows the encoding assembly located in the bottom portion of theinstrument which provides tracking and control of the cartridge rotorplate.

FIG. 23 is a perspective view of the bar code reader which is located inthe top portion of the instrument.

FIG. 24 is an alternate perspective view of the bar code reader shown inFIG. 23 with the light-emitting diodes (LED) on one side being exposed.

FIG. 25 is a perspective view of the housing plates which surround thecartridge rotor plate. The housing plates include heating elements whichare operated to maintain controlled temperature during processing of thecartridges.

FIG. 26 is an exploded view of the preferred exemplary sample transportactuator system in accordance with the present invention.

FIG. 27 is a perspective view of the assembled sample transportactuator.

FIG. 28 shows vent actuator block which forms part of the sampletransport actuator mechanism.

FIG. 29 shows the preferred exemplary reagent pouch actuator and relatedactuating mechanism.

FIG. 30 is an exploded view of the reagent pouch actuator assembly shownin FIG. 29.

FIG. 31 is a perspective view of the cartridge rotor plate wherein theplatter caps have been removed to show the cartridge latching mechanism.

FIG. 32 is a detailed view of the sample cartridge ejection mechanism.

DETAILED DESCRIPTION OF THE INVENTION

A preferred exemplary analytical instrument in accordance with thepresent invention is shown generally at 10 in FIG. 1. The outer housingof the instrument is shown in more detail in copending design patentapplication Ser. No. 29/100,499, now U.S. Design Pat. No. D424956. Theinstrument is designed to receive and process self-contained analyticalcartridges such as those shown generally at 12. The cartridges 12include test elements which utilize reflectance, transmittance orelectrochemistry. The transmittance type analytical cartridge is shownin FIGS. 8-10 and 12. This type of cartridge is also described in detailin international application No. PCT/US98/15616. This type of cartridgewill also be described briefly below.

The type of analytical cartridge which utilizes an electrochemical testelement is shown in FIGS. 11, 13 and 14. Such electrochemical testcartridges are also described in copending patent application Ser. No.09/079,034, which was filed on May 14, 1998, and is published asInternational patent application No. US99/06207. The electrochemicalcartridge will also be briefly described below. The transmittance typeanalytical cartridge is shown in FIGS. 15-17. This type of cartridge isalso described in detail in International patent application No.PCT/US99/01707.

The detailed descriptions of the three types of analytical cartridgesset forth in the above three pending applications are herebyincorporated by reference. The brief description of these cartridges setforth later on in the body of this specification is provided to show howa preferred exemplary embodiment of the present analytical instrumentoperates. It will be understood by those skilled in the art that theanalytical instrument of the present invention may be utilized foranalyzing other analytical cartridges which have similar properties tothe preferred exemplary cartridges described herein and set forth in theabove-referenced patent applications.

Referring again to FIG. 1, the analyzer 10 includes an upper housingcover 14 and a lower housing cover 16. A computer input/output pad orscreen 18 is located in the upper cover 14 to allow the operator of theinstrument to view information and input. The housing cover 14 furtherincludes an inlet port 20 through which the cartridges 12 are insertedinto the instrument. A central processing unit is located within theupper housing cover 14. A disc inlet 22 is provided for allowing theoperator to insert floppy disks into the central processing unit toprovide software updates as well as transport other data and informationinto and out of the central processing unit. The upper housing cover 14also includes a port and shelf 24 where a paper copy of report resultsand other data is made available to the operator.

The analyzer is shown in FIGS. 2-4 with the housing covers and centralprocessing unit removed. The instrument includes a cartridge carouselassembly shown generally at 26, a detector assembly located below thecartridge carousel assembly 26 and shown generally at 28 and a trackingand control unit which is located in the bottom of the instrument and isshown generally at 30. The tracking and control system 30 includes twocircuit boards 29 and 31 which are connected to the central processingunit and a real-time processor to provide overall tracking and controlfunctions for the instrument.

The cartridge carousel assembly includes a cartridge rotor plate 32, arotary drive mechanism 34 and sample/reagent actuators 36. A retractabledoor 35 is provided which can be lowered to allow cartridges 12 to beintroduced into the rotor plate 32. As shown in FIG. 5, the rotary drivemechanism 34 includes a motor and pulley assembly 38 which drives belt40 and pulley 42 which is connected to driveshaft 44. The cartridgerotor plate 32 is connected to the driveshaft 44. An encoding assembly46 is provided to track the position of the cartridge rotor plate 32 andprovide outputs which are part of the tracking and control system whichoperate motor 38 to provide controlled stopping and rotation ofcartridge rotor plate 32 at various times and at various speeds.

The cartridge rotor plate 32, as best shown in FIGS. 6, 7 and 31,includes a center 48 and a plurality of cartridge ports 50 which arelocated in spaced relation radially outward from the center 48. Thecartridge ports 50 are shaped to receive the analytical cartridges whichare shown in FIGS. 8-17. An exemplary cartridge 12 is shown in positionwithin the cartridge rotor plate 32 (see FIG. 6). The rotor plate 32includes locking tabs 52 which are located on either side of port 50.The locking tabs 52 engage the sides of cartridge 12 to lock it in placeduring centrifugation of the cartridges. The rotor plate 32 furtherincludes balance weights 54 which are connected to a support yoke 56.

The cartridge ports 50 are divided into two sections. An outer cartridgedock 58 and an inner balance weight dock 60. When the cartridge 12 isinserted into the cartridge dock 58, as shown in FIG. 6, the balanceweight 54 and yoke assembly 56 are pushed via a yoke mounting track intothe balance weight dock 60. The movement of the balancing weight 54 andyoke 56 from the cartridge dock 58 into the balance weight dock 60 isrepresented by arrow 62 in FIG. 7. The yoke 56 is held in place andguided by top plates 57. In FIG. 31, the rotor plate 32 is shown withthe top plates 57 being removed.

As the cartridge 12 is moved into dock 58, it contacts tabs 52 andpushes the tabs 52 outward. The tabs 52 are connected to arms 53. Thearms 53 include inner tabs 64 which are spring-biased inward by springslocated between the arms at 55 in FIG. 31. The springs are not shown.Once the cartridge 12 reaches its final location in dock 58, the tabsare spring-biased into locking engagement with indentations in thecartridge 12. The inner tabs 64 are located so that they do notinterfere with movement of the weight 54 into the balance weight dock60.

If a cartridge 12 is not inserted into dock 58, the balance weight 54and yoke 56 remain within the cartridge dock 58 during rotation of plate32. This provides balancing of the plate 32 to substantially reducevibration and prevent possible damage which might occur duringhigh-speed rotation of an unbalanced plate. This counterbalance systemallows the operator to insert as few as one cartridge into theinstrument for analysis or as many as six. An even larger number ofcartridges can be inserted into the cartridge rotor plate if the numberof ports is increased. Referring to FIG. 6, the balance weight locatedin the port 50 which is adjacent to the cartridge 12 (counterclockwise)is shown located within the balance weight dock 60. Upon initialrotation, this particular counterweight will slide outward into thecartridge dock 58 to provide balancing of the plate 32.

As mentioned above, the cartridges 12 which are processed by theanalytical instrument of the present invention can be of at least threetypes. The first type is shown at 66 in FIGS. 8-10 and 12. The cartridge66 includes a body 68, top plate 70, label 72 and cover 74. The concavecurve in the cartridge body sides may be eliminated as shown in phantomat 75 in FIG. 10, if desired. The cartridge includes a samplemetering/separation system which is shown at 76 in FIG. 8. The sample isintroduced into the system 76 through sample introduction portion 78.The system also includes a vent port 80 which is required for properoperation of the system.

The system 76 is designed to meter out an accurate sample aliquot whenthe cartridge is subjected to centrifugation. In addition, the system 76is designed to provide separation of solid components, such as bloodcells, from the sample during centrifugation, if desired. The cartridge66 also includes a flexible septum 82 which forms an essential part ofthe cartridge's pressure-operated sample transport system. As will bedescribed in more detail below, the analytical instrument of the presentinvention includes a sample transport actuator which compresses septum82 in order to pressurize the system 76 and transport thepreviously-metered sample to the test element. The two basic steps ofthe analytical process are centrifugation of the cartridge to achievemetering and separation of the sample followed by pressurization ofsystem via septum 82 to transport the sample to the test element.

The test element for cartridge 66 is reflectance reagent plate 84 whichis held in place within the cartridge by retainer 86. Pressurization ofseptum 82 transports the sample through system 76 into contact with thereagent plate 84. The result is a detectable analytical property. Thisanalytical property is measured by the analytical instrument, as will bedescribed in more detail below, by focusing radiation of a selectedwavelength onto plate 84 and measuring the amount of radiation which isreflected back to a detector. Both the radiation source and reflectancedetector are located below the cartridge rotor plate 32.

A second type of analytical cartridge is shown at 88 in FIGS. 11, 13 and14. Cartridge 88 is similar to cartridge 66 in that it requirescentrifugation followed by pressurization in order to carry out analysisof a given sample. The principal differences are that the cartridge 88includes a system for transporting reagent to the test element and,instead of using a reflectance test element, cartridge 88 utilizes anelectrochemical measuring device.

The electrochemical analytical cartridge 88 includes a body 90, topplate 92, cover 94 and flexible septum 96. The cartridge 88 alsoincludes a flexible reagent pouch 98 which is compressed and puncturedby a reagent transport actuator to transport reagent to theelectrochemical detector which is shown at 100 in FIG. 14. Likecartridge 66, cartridge 88 also includes a label 104. Both labels 104 oncartridge 88 and label 72 on cartridge 66 preferably include a bar codewhich is shown at 106 in FIG. 12. This bar code is read by theinstrument to provide input of data which is specific to the particularcartridge. This information is used by the tracking and control systemof the analytical instrument to coordinate the rotary drive mechanismfor the cartridge rotor plate and the actuators which operate againstthe flexible septums and flexible reagent pouches.

The electrochemical cartridge 88 also includes a sample inlet port 108and vent port 110. The sample metering and transport system is shown at112 in FIG. 13. This system typically does not include the plumbingrequired for separation of solid components from the sample because, ingeneral, electrochemical tests do not require separation of solids fromthe sample. However, the system shown at 112 may be modified to providesample separation, if desired.

The cartridge cover 94 is opened in order to allow the operator to placea sample into the cartridge through port 108. The cover is then closedas shown in FIG. 12 and the cartridge inserted into one of the ports 50in cartridge rotor plate 32. The cartridge is then centrifuged atsufficient speeds and for a sufficient time to meter out an accurateamount of sample within system 112. Septum 82 is then actuated totransport sample liquid to the electrochemical detector 100. Inaddition, flexible reagent pouch 92 is also compressed. Compression offlexible pouch 98 causes the pouch to be punctured and reagent to betransported to the electrochemical detector 100. The instrument includesan electrochemical detector probes, which will be described in furtherdetail below. The probes contact the electrochemical detector 100 tomeasure the results of electrochemical testing.

A third type of exemplary cartridge which is processed by the analyticalinstrument of the present invention is shown in FIGS. 15-17. This typeof cartridge is a transmittance-type analytical cartridge which is shownat 114 in FIG. 15. The transmittance cartridge 114 includes a cartridgebody 116, top plate 118, cover 120 and septum 122. The transmittancecartridge 114 further includes a cuvette 124 which is held in place byretainer 126. The cuvette 124 is a test element which is capable ofbeing exposed to spectral radiation in order to providespectrophotometric test results. The cuvette 124 is shown in more detailin FIGS. 16 and 17.

The cuvette 124 includes optical wings 128 and 130 which direct spectralradiation through the cuvette test zone or cell 132 as shown by phantomline 134 in FIG. 17. As will be described in detail below, theanalytical instrument of the present invention includes a detectorsystem which has a spectral radiation source shown schematically at 136in FIG. 17 which is located below the cartridge rotor plate 32. Thespectral radiation source directs a focused beam of radiation 134 up towing 130 which in turn directs the beam through the cuvette test zone ortest cell 132 to wing 128 and back down to a detector shownschematically in FIG. 17 at 138.

The internal operation of the three types of cartridges have only beenbriefly described above in order to provide an understanding of theoperation of the analytical instrument 10. A more detailed descriptionof the three types of cartridges can be found in the above-referencedInternational patent applications.

A bottom view of the upper portion 140 of the cartridge carouselassembly 26 is shown in FIG. 18. The upper portion 140 is also shown inplace on instrument 10 in FIG. 2. A sample transport actuator is showngenerally at 141 in FIGS. 2, 18 and 26. The actuator 141 includes aseptum actuator rod 142 is provided which is movable into contact withthe flexible septums on the analytical cartridges to move the septumsfrom a relaxed position to one or more compressed positions to providetransport of metered and/or separated samples to the cartridge testelement. A vent seal rod 146 is also provided which is designed tocontact and seal the cartridge vent which is shown at 80 in FIG. 8, 110in FIG. 11 and not shown on the cartridge in FIG. 15.

As best shown in FIGS. 26-28, the sample transport actuator mechanism141 includes a motor 143, pusher cover 145, vent block 147, main pusherblock 149, vent block spring 151 and vent seal rod spring 155. The ventseal rod 146 includes a tip 163. The block 149 is moved up and down bymotor 143 via drive shaft 165. As best shown in FIG. 27, the vent sealrod tip 163 extends below the tip of the septum actuator rod 142. As aresult, the vent seal rod tip 163 contacts and seals the cartridge ventprior to the septum actuator rod 142 compressing the flexible septum. Itis necessary that the cartridge vent be closed prior to compression ofthe flexible septum. Otherwise, adequate pressurization of the cartridgemay not be achieved to provide desired sample transport.

In addition, the sample transport actuator mechanism 141 must alsoprovide for retraction of vent seal rod 146 from its sealing positionagainst the cartridge prior to retraction of the septum actuator rod142. By retracting the vent seal rod 146 first, pressure within theanalytical cartridge is released uniformly. This eliminates thepossibility of disturbing liquids within the cartridge plumbing due topremature movement of the flexible septum back to the septum's initialrelaxed position. A wide variety of different possible mechanisms arepossible to achieve this condition wherein the vent seal rod provides aseal prior to septum compression and releases the seal prior to septumrelaxation. However, it is preferred that a solenoid-operated releasesystem be used as shown in FIGS. 26 and 27. This system employs asolenoid 148 which operates a push lever 167 which is connected to sealrod 146 by lever spring 169. Operation of solenoid 148 moves lever 167which releases the vent seal rod 146 so that it moves upward in ventblock 147. Once the vent seal rod 146 is released, the main pusher block149 is withdrawn to release the septum rod 142 from contact with thecartridge septum. To reset the vent seal, the vent seal rod 146 is movedto the position shown in FIG. 27, where a reset pin 177 is pushedagainst reset bar 179.

A reagent transport actuator is shown generally at 183 in FIGS. 18, 29and 30. The reagent actuator 183 includes a reagent pouch actuator rod150. The reagent actuator rod 150 is controlled by actuator motor 152.The rod 150 and actuator motor 152 form a reagent actuator mechanismwhich moves the reagent pouch on the analytical cartridge from a relaxedposition to one or more compressed positions. A tip 185 is placed overthe rod 150. The tip 185 is connected to a block 187. A spring 189biases the tip 185 away from rod 150. During compression of the reagentpouch, the spring 189 becomes slightly compressed as the tip 185 isseated against the rod 150.

During compression of the reagent pouch, a spike or other element in thecartridge punctures the reagent cartridge to allow release andpressurized transport of the reagent. The spring 189 provides a constantpressure bias against the pouch even as it is punctured and releasesfluid. The reagent actuator rod 150, septum actuator rod 142 and ventseal rod 146 are all shown in their retracted position in FIG. 18. Thevarious rods are moved into contact with the cartridges as controlled bythe tracking and control system of the instrument. The system iscoordinated so that the actuator rods only move into contact with acartridge when the cartridge rotor plate 32 is stationary. If desired,additional reagent pouch actuators and associated actuator mechanismsmay be included in the instrument to handle cartridges which may havetwo or more reagent pouches which require simultaneous actuation.

Ejection of cartridges 12 from rotor plate 32 is accomplished by anejection mechanism which is shown at 153 in FIGS. 18 and 32. Themechanism 153 includes an ejection arm 154, guide rod 155 and drivemotor 156. The actuator arm 154 is shown in a retracted position. Theactuator arm 154 moves in the direction of arrow 157. The ejectionactuator arm 154 is operated by motor mechanism 156. The actuator arm154 ejects the cartridge 12 by first moving inner tabs 64 outward.Movement of inner tabs 64 outward also moves arms 53 and attached tabs52 outward to release cartridge 12. The actuator arm 154 continues tomove outward to move the counter weight 54 to the position shown in FIG.7 and eject cartridge 12. The tracking and control unit of theinstrument controls the ejection mechanism 153 and rotary drivemechanism 34 so that the cartridges are only ejected when they arelocated at ejection port 159 (see FIGS. 2 and 4).

A magnetic mechanism 161 is located adjacent to the ejector 153. Themagnet 161 is used in combination with magnetic particles which may beincluded in the cartridges to provide mixing of reagents and sampleswithin the cartridges as they pass by the magnet.

A preferred exemplary optical detector is shown at 158 in FIG. 19. Theoptical detector 158 is located directly below the cartridge carouselassembly 26. The optical detector 158 includes seven LED's 160. Theoptical detector 158 further includes collimator elements 164 and 166which direct spectral radiation from the LED upward through the detectoras represented by phantom line 168. The radiation path for only thecentral LED is shown. The collimating elements 164 and 166 direct theother LED beams in the same manner. The detector 158 further includes abeam control plate 170 which includes six slits 172 and one smaller slit162. The slits 172 and 162 further reduce the size of LED beams 168 sothat the final radiation beams 168 which contacts the test element ofthe analytical cartridge has a small cross-sectional area. The testelement of the analytical cartridge is shown diagrammatically at 174 inFIG. 19. The slit 162 is smaller than the other slits and is designedfor use with cartridges that include a cuvette.

The test element, as described above, may include either a reflectancetest element or a transmittance test element (i.e., the cuvette 124shown in FIGS. 16 and 17). The optical detector 158 further includes areturn beam detector plate 176 which includes four optical detectorelements 178. The return beam from analytical cartridge 174 travelsthrough openings 181 in beam control plate 170. The path of thereturning beam of transmitted or reflected spectral radiation is shownin phantom at 180. Again, for simplicity, the return beam path 180 isshown for only one of the LED's 160.

A wide variety of radiation sources may be utilized. In the preferredexemplary embodiment, the light-emitting diodes 160 each have adifferent wavelength. For example, moving from right to left in FIG. 19,the light-emitting diodes will have wavelengths of 425 nanometers, 505nanometers, 570 nanometers, 590 nanometers, 615 nanometers, and 655nanometers. The LED 160 on the far left is used for cuvette cartridgesand preferably emits a wavelength of 570 nm. This range of LEDwavelengths is preferred since it provides measurement beams rangingfrom near-ultraviolet through the visible spectrum to near-infraredwavelengths. A wide variety of LED combinations is possible dependingupon the types of tests being conducted. The tracking and control unitis programmed, depending upon the particular test cartridge beinganalyzed, to expose the cartridge to one or more of the LED wavelengths.In this way, a wide variety of spectrophotometric measurements can bemade.

As shown in FIG. 19, the optical detector 158 is arcuate in shape. Thearcuate shape of the optical detector 158 is matched to the arcuate pathof the cartridges as they move during rotation of the cartridge rotorplate 32. In this way, measurements may be taken when the cartridge isstationary or when the cartridge is moved past the detector duringrotation of the rotor plate 32. The instrument may be programmed so thatmultiple measurements of the test element 174 may be made as it movespast the optical detector slits 172. In this way, measurements from oneend of the test element to the other can be taken as the test elementmoves past a particular slit 172. Alternatively, the cartridge testelement 174 may be held stationary over the optical detector 158 andtime-dependent changes in spectral transmittance or reflectance may bemeasured. It is preferred that the cross-sectional area of slits 172 besubstantially less than the cross-sectional area of theoptically-accessible portion of the test element 174 present in theanalytical cartridge. For example, the cross-sectional area of slit 172should be at least one-tenth of the cross-sectional area of theoptically-accessible portion of test element 174. Test beams havingcross-sectional areas which are on the order of one-hundredth of thecross-sectional area of the optically-accessible portion of the testelement are also possible.

A preferred exemplary electrochemical detector is shown at 182 in FIGS.20 and 21. The electrochemical detector 182 is located directly belowthe cartridge carousel assembly 26 as shown in FIGS. 2 and 4. Theelectrochemical detector 182 includes electrical contact probes 184which are designed to be moved by actuator mechanism 186 into contactwith the electrochemical detector 100 located on the bottom ofelectrochemical cartridge 88 (FIG. 14). The instrument tracking andcontrol system is set up so that the electrical probes 184 are onlymoved into position by actuator 182 when an electrochemical cartridge isbeing tested. Further, the instrument is programmed so that theelectrical probes 184 are only moved into position when the cartridge islocated over the electrochemical detector 182 and is stationary.

As part of the tracking and control system, the analytical instrumentwill preferably include a spindle positioning encoder which is shown at188 in FIG. 22, and more generally at 46 in FIG. 5. The encoder isconnected to the circuit boards of the tracking and control unit 30which are in turn connected with the central processing unit. Theencoder 188 is connected to spindle 44 which in turn is connected to therotor plate 32. A transparent optical disk 190 is provided which hasindexing marks 192 which include a home index mark 194. A light source196 with corresponding optical detector 198 are provided to detectpassage of the index marks past the optical detector. The combined lightsource and optical detector 196 and 198 provides continual input to thereal-time processing unit and central processor which allows accuratecontrol of rotation speeds and radial location of cartridges, when theyare located within the cartridge rotor plate. Other encoder systems arepossible, provided that they are capable of providing the same trackinginformation which is input into the tracking and control system in orderto accurately control rotation and positioning the cartridge rotor plate32.

The analytical instrument includes a bar code reader which is shown at200 in FIGS. 2-3 and 23-24. The bar code reader 200 scans arcuate barcodes 201 on the analytical cartridges to provide input into thetracking and control system regarding the type of cartridge and tests tobe run (see FIG. 6). The bar code reader 200 also reads a Z-shapedposition calibration label 202 on the rotor plate 32 (FIG. 6). The barcode reader 200 preferably utilizes a 1:1 ratio double-lens camera and alight source such as LED's 204. The bar code reader also includes aphotodiode light detector 206. As the alternating light and darksegments of the bar code 201 pass before the bar code reader 200, theyare illuminated by, the light source 204 and projected onto thephotodiode detector chip 206 as a series of light pulses. The detectorchip 206 is preferably a linear array of 128 photodiode elementsoriented such that light reflected from each bar code element shinesupon about three or more photodiode elements. The bar code reader 200 isalso adapted to scan the Z-shaped position calibration label 202 on thespinning rotor plate 32. The bar code reader 200 in conjunction with theencoder 188 provide input into the central processing unit and/orreal-time processor which allows the position of the rotor plate to beaccurately determined and controlled.

It is preferred that the cartridge rotor plate be maintained at constanttemperature. For many cartridges, test results will vary if thetemperature is not kept constant. In addition, some tests must beconducted at elevated temperatures. Accordingly, it is preferred thattwo heating plates 210 and 212 be located on either side of thecartridge rotor plate 32 as shown in FIG. 25. The heater plates orplatens are preferably electrically heated. However, other types oftemperature control systems may be used. The spinning of the rotor plateat relatively high speeds (e.g. 1500 rpm) facilitates heating because ofthe uniform and constant mixing of air and heat generated by the rotor.

Having thus described exemplary embodiments of the present invention, itshould be noted by those skilled in the art that the within disclosuresare exemplary only and that various other alternatives, adaptations, andmodifications may be made within the scope of the present invention.Accordingly, the present invention is not limited to the specificembodiments as illustrated herein, but is only limited by the followingclaims.

What is claimed is:
 1. An analytical instrument for analyzing fluids,said instrument comprising: A) a cartridge carousel assembly whichreceives analytical cartridges, said cartridges comprising an analyticalsystem which requires centrifugal force to operate and a test elementwhich provides a detectable analytical property of said fluid, saidcartridge carousel assembly comprising: a) a cartridge rotor plate whichcomprises a center and a plurality of cartridge ports which are locatedin spaced relation radially outward from said center, said cartridgeports comprising a cartridge dock having radially extending side wallsdefining a cartridge chamber which is shaped to receive said cartridgesand a balance weight dock which is located radially inward from saidcartridge dock, said balance weight dock having radially extending sidewalls defining a balance weight chamber which is shaped to receive abalance weight; b) a rotary drive mechanism which rotates said cartridgerotor plate about the center thereof, wherein rotation of said cartridgerotor plate provides the centrifugal force required to operate theanalytical system of said cartridge; c) a locking mechanism which holdssaid cartridge in said cartridge chamber during rotation of saidcartridge rotor plate; d) a balancing mechanism which comprises abalance weight wherein said balance weight is movable to said balanceweight chamber when said cartridge is inserted into said cartridgechamber and wherein said balance weight remains in said cartridgechamber during rotation of said cartridge rotor plate when a cartridgeis not present in said cartridge chamber, and wherein the distancebetween the radially extending side walls of said cartridge chamber isgreater than the distance between the radially extending side walls ofsaid balance weight chamber, said balancing mechanism comprising asupport yoke to which said balance weight is attached for movementbetween said cartridge chamber and balance weight chamber and a supportyoke track located in each of the radially extending side walls of saidcartridge chamber and said balance weight chamber, said support yokebeing mounted within said support tracks to provide slidable movement ofsaid support yoke in said support yoke tracks between said cartridgechamber and said balance weight chamber; and e) an ejection mechanismwhich ejects said cartridge from said cartridge port; B) a detectorwhich measures said detectable analytical property of said fluid samplewhich is provided by the test element of said cartridge; and C) atracking and control unit which tracks and controls said rotary drivemechanism, said locking mechanism and said ejection mechanism, saidtracking and control unit comprising a user input interface forreceiving data input from a user of the instrument, a central processingunit, a real time processor and a data output interface which providesoutput of results of the measurements made by said detector.
 2. Ananalytical instrument for analyzing fluids according to claim 1 whereinsaid locking mechanism comprises a pair of spring-biased latches whichare biased into locking engagement with said cartridge when saidcartridge is located in said cartridge chamber.
 3. An analyticalinstrument for analyzing fluids according to claim 2 wherein saidejection mechanism comprises an ejection arm which contacts saidspring-biased latches to release said latches from said lockingengagement.
 4. An analytical instrument for analyzing fluids accordingto claim 1 which is adapted for use with cartridges that comprise a topside, bottom side, an analytical system which requires centrifugal forceto operate and a test element which comprises an optical element whichis optically accessible from only one side of said cartridge and whereinsaid optical element provides an optically detectable analyticalproperty of said fluid, said detector comprising: an optical detectorwhich measures said detectable analytical property of said fluid samplewhich is provided by the optical element of said cartridge, said opticaldetector comprising: a) a radiation source located relative to saidcartridge rotor to provide an incident beam of radiation which contactssaid optical element and wherein a return beam of radiation is emittedby said optical element in response to contact by said incident beam ofradiation; and b) a return beam detector which measures said return beamof radiation wherein said radiation source and return beam detector areboth located on the same side of said cartridge when it is locatedwithin said cartridge rotor plate; and wherein said tracking and controlunit tracks and controls said rotary drive mechanism and said detectorto provide coordinated operation so that said optical detector can makemeasurements of said optical element while said cartridge rotor isstationary or rotating.
 5. An analytical instrument according to claim 4wherein said radiation source comprises: a plurality of light emittingdiodes which are arranged to form an arcuate array of light emittingdiodes which corresponds to the arcuate path of said optical element assaid cartridge travels in said cartridge rotor plate during rotation ofsaid cartridge rotor plate.
 6. An analytical instrument according toclaim 5 wherein said radiation source comprises one or more lightemitting diodes which emit radiation in a wavelength selected from thegroup consisting of ultra-violet, visible and infra-red.
 7. Ananalytical instrument according to claim 6 wherein said radiation sourcecomprises: a first light emitting diode which emits radiation consistingof a wavelength of about 425 nanometers; a second light emitting diodewhich emits radiation consisting of a wavelength of about 505nanometers; a third light emitting diode which emits radiationconsisting of a wavelength of about 570 nanometers; a fourth lightemitting diode which emits radiation consisting of a wavelength of about590 nanometers; a fifth light emitting diode which emits radiationconsisting of a wavelength of about 615 nanometers; a sixth lightemitting diode which emits radiation consisting of a wavelength of about655 nanometers.
 8. An analytical instrument according to claim 4 whereinthe optically accessible portion of said optical element has across-sectional area and wherein said radiation source comprises acollimator which directs said incident beam of radiation onto saidoptical element as collimated incident beam which has a cross-sectionwhich is substantially less than the cross-section of said opticallyaccessible portion.
 9. An analytical instrument according to claim 8wherein said tracking and control unit is set to take multiplemeasurements of the optical element by exposing said optical element toa plurality of collimated incident beams and measuring the resultantplurality of return beams.
 10. An analytical instrument for analyzingfluids according to claim 1 which is adapted for use with cartridgesthat comprise a top side, bottom side, an analytical system whichrequires centrifugal force to operate and a test element which comprisesan electrochemical element which is electrically accessible from onlyone side of said cartridge and wherein said electrochemical elementprovides an electrically detectable analytical property of said fluid,said detector comprising: an electrical detector which measures saidelectrically detectable analytical property of said fluid sample whichis provided by the electrochemical element of said cartridge, saidelectrochemical detector comprising: a) an electrical probe comprising asurface which is movable between a retracted position and an extendedposition where said electrical probe is in contact with saidelectrochemical element to provide measurement of said electricallydetectable analytical property; and b) a probe actuator assemble whichmoves said electrical probe between said retracted position and saidextended position; and wherein said tracking and control unit tracks andcontrols said rotary drive mechanism and said electrical detector toprovide coordinated operation so that said electrical detector can makemeasurements of said electrochemical element while said cartridge rotoris stationary.
 11. An analytical instrument for analyzing fluidsaccording to claim 4 wherein said instrument is also adapted for usewith cartridges that comprise a top side, bottom side, an analyticalsystem which requires centrifugal force to operate and a test elementwhich comprises an electrochemical element which is electricallyaccessible from only one side of said cartridge and wherein saidelectrochemical element provides an electrically detectable analyticalproperty of said fluid, said detector comprising: an electrical detectorwhich measures said electrically detectable analytical property of saidfluid sample which is provided by the electrochemical element of saidcartridge, said electrochemical detector comprising: a) an electricalprobe comprising a surface which is movable between a retracted positionand an extended position where said electrical probe is in contact withsaid electrochemical element to provide measurement of said electricallydetectable analytical property; and b) a probe actuator assemble whichmoves said electrical probe between said retracted position and saidextended position; and wherein said tracking and control unit tracks andcontrols said rotary drive mechanism and said electrical detector toprovide coordinated operation so that said electrical detector can makemeasurements of said electrochemical element while said cartridge rotoris stationary.
 12. An analytical instrument for analyzing fluidsaccording to claim 4 wherein said instrument is adapted for use withcartridges that comprise a centrifugal force operated samplemetering/separation system and a pressure operated sample transportsystem and wherein rotation of said cartridge rotor plate activates saidcentrifugal force operated sample metering/separation system, saidanalytical instrument comprising: a sample transport actuator whichactivates the pressure operated sample transport system of saidcartridge; and wherein said tracking and control unit tracks andcontrols said rotary drive mechanism and sample transport actuator toprovide coordinated operation of said centrifugal force operated samplemetering/separation system and said pressure operated sample transportsystem wherein said coordinated operation provides delivery of a meteredamount of sample fluid to the test element of said cartridge.
 13. Ananalytical instrument for analyzing fluids according to claim 12 whereinsaid instrument further comprises a reagent transport actuator whichactivates a pressure operated reagent transport system which is presentin said cartridge and wherein said tracking and control unit providestracking and control of said rotary drive mechanism, pressure operatedsample transport system and pressure operated reagent transport systemwherein said coordinated operation provides delivery of a metered amountof sample fluid and an aliquot of reagent to the test element of saidcartridge.
 14. An analytical instrument for analyzing fluids accordingto claim 12 wherein said sample transport actuator activates a pressureoperated sample transport system which comprises a flexible septum whichcan be moved from a relaxed position to one or more compressed positionswherein movement from said relaxed position to said one or morecompressed positions provides pressurization of said sample transportsystem and wherein said cartridge further comprises a vent for saidsample metering/separation system, said sample transport actuatorcomprising: a septum actuator having a surface which is movable intocontact with said flexible septum to move said septum from said relaxedposition to said one or more compressed positions; a vent seal elementhaving a surface which is movable to a position which seals said vent;and a sample actuator mechanism which jointly moves said septum actuatorand vent seal element to provide movement of said flexible septum andsealing of said vent wherein said vent is sealed prior to movement ofsaid septum from said relaxed position.
 15. An analytical instrument foranalyzing fluids according to claim 14 wherein said instrument furthercomprises a reagent transport actuator which activates a pressureoperated reagent transport system which is present in said cartridge,said reagent transport system comprising a flexible pouch which can bemoved from a relaxed position to one or more compressed positions toprovide movement of reagent within said cartridge, said reagenttransport actuator comprising: a reagent pouch actuator having a surfacewhich is movable into contact with said reagent pouch to move said pouchfrom said relaxed position to one or more of said compressed positions;and a reagent actuator mechanism which moves said reagent pouch actuatorinto contact with said reagent pouch to provide movement of said pouchfrom said relaxed position to one or more of said compressed positions.16. An analytical instrument for analyzing fluids according to claim 14wherein said septum actuator comprises a septum rod comprising a tipwhich comprises said surface which is movable into contact with saidseptum, said vent seal element comprises a seal rod comprising a tipwhich comprises said surface which seals said vent and said sampleactuator mechanism comprises: a connector block which connects saidseptum rod to said seal rod; a sample actuator motor which moves saidmain pusher block so that said septum rod and seal rod move betweenretracted positions and extended positions where said septum rod is incontact with said septum and said seal rod is in contact with said vent;and a release mechanism which orients said seal rod tip so that itcontacts said vent before said septum rod tip compresses said septum andwherein said spring mechanism withdraws said seal rod from contact withsaid vent prior to withdrawal of said septum rod from contact with saidseptum during retraction of said septum rod and seal rod from saidextended positions to said retracted positions.
 17. An analyticalinstrument according to claim 15 wherein said reagent pouch actuatorcomprises a reagent rod comprising a tip which comprises said surfacewhich is movable into contact with said reagent pouch and said reagentactuator mechanism comprises a reagent actuator motor which moves saidreagent rod between a retracted position and extended positions wheresaid reagent rod tip is in contact with said reagent pouch.
 18. Ananalytical instrument for analyzing fluids according to claim 10,wherein said instrument is adapted for use with cartridges that comprisea centrifugal force operated sample metering/separation system and apressure operated sample transport system and wherein rotation of saidcartridge rotor plate activates said centrifugal force operated samplemetering/separation system, said analytical instrument comprising: asample transport actuator which activates the pressure operated sampletransport system of said cartridge; and wherein said tracking andcontrol unit tracks and controls said rotary drive mechanism and sampletransport actuator to provide coordinated operation of said centrifugalforce operated sample metering/separation system and said pressureoperated sample transport system wherein said coordinated operationprovides delivery of a metered amount of sample fluid to the testelement of said cartridge.
 19. An analytical instrument for analyzingfluids according to claim 11, wherein said instrument is adapted for usewith cartridges that comprise a centrifugal force operated samplemetering/separation system and a pressure operated sample transportsystem and wherein rotation of said cartridge rotor plate activates saidcentrifugal force operated sample metering/separation system, saidanalytical instrument comprising: a sample transport actuator whichactivates the pressure operated sample transport system of saidcartridge; and wherein said tracking and control unit tracks andcontrols said rotary drive mechanism and sample transport actuator toprovide coordinated operation of said centrifugal force operated samplemetering/separation system and said pressure operated sample transportsystem wherein said coordinated operation provides delivery of a meteredamount of sample fluid to the test element of said cartridge.